Conventionally, laser light sources have mainly been applied to those utilizing focusing property of laser light and height of coherent light, such as measurement, optical communication, and optical disc. However, research and development of laser light sources are remarkable, and small-size high-output laser light sources represented by semiconductor lasers have advanced to practical use. Taking a semiconductor laser as an example, there is a multimode semiconductor laser that achieves an output of several W class, although its output wavelength is limited.
With reduction in size and increase in output power of laser light sources, exploitation of applications as well as development of devices using the small-sized and high-output laser light sources have been intensified.
High-output light sources are expected to be applied to various uses such as image display devices, lighting devices, semiconductor exposure devices, and the like. Particularly, realization of a clear image having high chromatic purity by a laser display using a high-output laser of three primary colors, i.e., R, G, and B, has been sought, utilizing monochromaticity of a high-output laser light source. Further, it is also expected to apply a small-sized and high-output laser light source to a low-power-consumption and long-life light source for lighting. Furthermore, the high-output laser light source is also applied to laser processing, and fine patterning using a high-output laser is being put to practical use.
In these applications using the high-output laser light sources, in addition to utilization of monochromatic characteristics and high-output characteristics of laser light are utilized, there has been strong demand for uniform cross-section light intensity distribution, and therefore, techniques that satisfy this demand have conventionally been proposed.
For example, Japanese Published Patent Application No.Hei.07-306304 (Patent Document 1) and Japanese Patent Publication No.3410813 (Patent Document 2) disclose a method of shaping light outputted from a laser light source having a Gaussian light intensity distribution so as to make the light intensity distribution uniform, using a device for homogenizing the light quantity, which is called a homogenizer. Further, Japanese Published Patent Application No.2002-40327 (Patent Document 3) and Japanese Published Patent Application No.2003-57514 disclose a method for shaping light outputted from a laser light source as described above, using an optical device called an integrator.